1. Field of the Invention
The present invention relates to a card connector and particularly to a card connector having a switch function during insertion/withdrawal of the related electrical card.
2. The Prior Art
Memory cards have become popularly due to the trend of compact size, modularization, and object oriented requirement of the computer industry. The memory cards are usually inserted into a card connector installed in a portable computer. For clearly identifying the insertion/withdrawal of the memory card with respect to the card connector, some card connectors are installed with a switch to more specifically control the electrical engagement/disengagement between the electrical card and the card connector. Such techniques are disclosed in U.S. Pat. Nos. 4,735,578, 4,752,234, 4,900,272, 4,900,273, 5,013,255, 5,334,034, 5,370,544, and 5,380,997. For example, U.S. Pat. No. 5,370,544 shown in FIG. 4 discloses a card connector 4 having a housing 40 in which a first metal plate 41 and a second metal plate 42 are fixed. Normally, the first and second plates 41, 42 are electrically connected to each other via respective end portions 411, 421. A protrusion 412 extends from the first plate 41 for receiving a force from an inserted card 5 so as to prevent the first plate 41 from contacting the second plate 42. A considerable contact resistance exists between the end portions 411, 421 of the plates 41, 42 because the contacting area therebetween is generally very narrow, similar to a line area. Moreover, the normal contact resistance will further increase due to the gradual loosening contact between the plates 41, 42 after extended use. If the contact resistance rises to a relatively large value, the switch may cause a malfunction of the related printed circuit board on which the card connected is mounted. Thus, it is requisite to provide a new switch for use in a card connector which will not malfunction due to a large contact resistance.